Rockwell chips / double marking : normal ?

[calculi]

Hello,

In this post viewtopic.php?f=1&t=1953&p=46961#p46961 I give some information about a disappointing experience with AliExpress, having ordered Rockwell parts. Besides other truly bad things I was surprised by 5 of the 10 R65C51 chips I received. They have a double marking, on both sides (as mentioned in my other post) :

Top : R65C51P4 / 11470-11 / MEXICO / 0212 A29587-3
Bottom : 11470 / 78647-4 or A31673-4/ MEXICO

I find that quite strange. No doubt that some fields are related to lot number / factory ID and so on... but why do they differ from one side to the other ? did some of you already encountered such chips ? Is it normal ? I'll warmly welcome any hint

Regards,
Marc

[GARTHWILSON]

calculi wrote:

[Have] some of you already encountered such chips ? Is it normal ? I'll warmly welcome any hint

I just looked at a bunch of Rockwell ones I've had for over 20 years, ones I have no doubt are authentic Rockwell ones. The ones with the larger (0.31" across) Rockwell logo on the top don't say anything on the bottom. The ones with the smaller (0.19" across) Rockwell logo on the top have writing on the bottom. I wonder if the writing on the bottom is from the lead frame manufacturer, printed before Rockwell got the lead frames and mounted their dice on them and then molded the top on. I don't really know how that process works. I worked in applications engineering in the mid-1980's at a place that made VHF & UHF power transistors, mostly for military radars and communication, and we bought the lead frames from another manufacturer and added our dice (ie, the actual chips) and added the bond wires and capped the parts.

[calculi]

Hello Garth,

Thank you for your answer ; anyway it seems that being absolutely sure is impossible, please have a look at BDD's thoughts : viewtopic.php?f=1&t=1953&p=46967#p46963

I checked my chips : the ones with writings on the bottom have a 0.235" logo, the other ones a 0.24" logo. I'm afraid that it doesn't help much !

Honestly, I wonder if making counterfeit obsolete chips makes sense, from a financial point of view ... ? is there so big a market for this 8-bit family ?

[BigDumbDinosaur]

calculi wrote:

Honestly, I wonder if making counterfeit obsolete chips makes sense, from a financial point of view ... ? is there so big a market for this 8-bit family ?

Unfortunately, the distribution of counterfeit chips is a really big problem, so much so that some distributors with which my company does business have invested in equipment to X-ray chips in a lot so as to determine their provenance.

[calculi]

I did some visual checks on the circuits I got from AliExpress : the more recent ones (from 2002 to 2008) are laser-marked, the older ones are ink-stamped. That would be kind of logical if there wasn't an exception : I've got genuine 65C51s from 2003 which are ink-stamped. Added to that, the circuits with double marking (top / bottom) share the 2 marking methods, bottom : ink / top : laser.

Another point, some circuits show (or pretend) that they were pulled from boards, by looking at the pins bending. They also went through some washing process which left traces along the edges.

To say the least, it's not easy to sort that out (if ever feasible)... What do you think about this -currently standard- laser-marking method ? Was it ever used by Rockwell ?

Thanks

Marc

PS : you may think that I'm beating a dead horse... I'm simply curious about (fair) manufacturing methods, among them the ones mentioned by Garth (lead frames...). Anyway I put a CPU and an ACIA on my test board (already fitted with a known-to-be-genuine VIA), found another dead ACIA (kept the CPU from starting), and I'll let it run for a few days. Wait and see.